Xiaomi Mi 9 SE is a compact flagship of 2019, which is still relevant thanks to powerful hardware and support for updates. But even the most reliable smartphones eventually degrade battery. If your Mi 9 SE began to run out in a few hours, overheat or shut down at 20-30% charge, it’s time to check the battery status.
In this article, you will find 5 working ways to diagnose a battery: from standard tools MIUI to the hidden engineering menus and ADB-We'll go into detail about what parameters are important (capacity, number of charging cycles, temperature), how to interpret them correctly and what to do if the battery is worn out, and at the end, answers to frequent questions and tips on extending the life of the battery.
1. Verification through standard MIUI settings
The easiest way is to use the built-in MIUI tools, which won't show the battery's exact capacity, but will help you measure its health by proxy.
Open Settings → Battery and Performance → Battery Use. Here you will see:
- 📊 Charge flow schedule – if the smartphone discharges too quickly even in standby mode, it is a sign of wear and tear.
- 🔋 Battery status assessment – in new versions MIUI It can be shown as “Good”, “Mediocre” or “Bad».
- ⚡ List of applications that consume charge – if even after the program is closed, they continue to “eat” the battery, this may indicate battery problems.
Note the battery life at the top of the screen. The Mi 9 SE is normal:
- 🔄 4-6 hours of active use (social networks, instant messengers, calls).
- 🌙 12-18 hours standby (without active use).
⚠️ Note: If the battery life is reduced by 2-3 times compared to the new smartphone, the battery is worn out by 50% or more. In this case, the standard settings will not give the full picture - move to the following methods.
2. Secret engineering codes for diagnostics
Xiaomi hides advanced battery data from users, but it can be obtained through service codes, which run on all Mi 9 SE smartphones regardless of the firmware version.
Open the Phone app and enter the following combinations:
##4636##
##284##Once you enter the first code, you will be taken to the Testing menu. Go to the Battery Information tab and notice:
- 🔋 Level of charge (level) – current percentage in digital form.
- ⚡ Voltage is the norm for the Mi 9. SE 3.7-4.3 B. If the value is below 3.5 V, the battery is severely worn out.
- 🌡️ Temperature (optimal 25–40)°C. Exceeding 45°C dangerously!
- 🔄 Technology: It must be Li-ion or Li-poly.
The second code (#284##) will open the battery and charger test.
- 🔌 Type of charging (fast/normal).
- ⚡ Charging current - for the Mi 9 SE 1.5-2.0 A for fast charging.
- 🔋 Battery status – can be displayed as Good, Normal or Replace (requires replacement).
⚠️ Note: If you enter the code and you see a message saying "No connection to the server", your firmware is blocking the engineering menu.
3.Use of applications for deep diagnostics
Standard MIUI tools provide limited information. For detailed analysis, use third-party applications. We tested 5 popular utilities and selected the two best for the Mi 9 SE:
AccuBattery (recommended)
The app analyzes the actual battery capacity, the number of charging cycles and the wear rate. Download it from Google Play and follow the instructions:
Install the application and provide all permissions
Charge your smartphone to 100% (important for calibration)
Discharge to 0% without recharging
Repeat the cycle 2-3 times for accurate data
Check the Health tab for wear assessment-->
After calibration, AccuBattery will show:
- 🔋 A percentage of battery health (e.g., 85% of initial capacity).
- 🔄 Number of charging cycles for Mi 9 SE criticality 500+ cycle.
- ⚡ Charging/discharge speed in mAh.
- 📊 Graphic wear for the entire period of use.
CPU-Z (alternative)
This app is better known as a hardware analysis tool, but it also shows accurate battery data. Download it here and go to the Battery tab.
- 🔋 Level - current charge.
- ⚡ Voltage - voltage.
- 🌡️ Temperature - Temperature.
- 🔄 Health – a condition (e.g., Good or Unknown).
The advantage of the CPU-Z is that it works without root rights and does not require calibration, but to assess wear, it is better to combine it with AccuBattery.
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If AccuBattery is below 80 percent and your smartphone is shutting down at 15 to 20 percent charge, that's a sure sign that it's time to change the battery. Don't wait for a complete failure: Lithium-ion batteries can swell and damage the motherboard.
4. Check through ADB (for advanced users)
If you want the most accurate battery data, use ADB (Android Debug Bridge), which requires connecting your smartphone to your computer, but gives you access to hidden settings that don't show the apps.
First, download Platform Tools from the official Android website and install drivers for Xiaomi Mi 9 SE. Then follow the following steps:
- Enable USB debugging on your smartphone: Settings → About Phone → MIUI Version (click 7 times to become a developer) → Settings → Additional → Developers → Debugging over USB.
- Connect the Mi 9 SE to your computer and confirm the debugging permission.
- Open the command line (Windows) or terminal (macOS/Linux) in the folder with the platform-tools.
- Enter the command to check the status of the battery: adb shell dumpsy battery
In the conclusion of the command, pay attention to the following parameters:
| Parameter | Description | Normal for Mi 9 SE |
|---|---|---|
| level | Current charge in % | 0–100 |
| voltage | Voltage in mV | 3700–4300 |
| temperature | Temperature in °C | 25–40 |
| charge counter | Real capacity in mkAh | 2800–3070 (for a new battery) |
| health | Battery status | 2 (good) |
The most important parameter is charge counter. Compare it to the passport capacity of the Mi 9 SE (3070 mAh). For example, if the value is 2000 mAh, then the battery is worn out by 35%.
⚠️ Note: If the health parameter is 3 (bad condition) or 7 (unknown), this may indicate a malfunction of the power controller.
What if the ADB does not recognize the device?
5. Visual Diagnostics: When the Battery Needs to Be Changed Urgently
Even if software methods show a "normal" state, the physical wear of the battery can be critical.
- 🔋 Bloating - if the back cover or screen starts to "go away" it's dangerous.
- 🌡️ Overheating - if Mi 9 SE heats up above 50°C without load (check through the engineering menu).
- ⚡ Unintentional shutdowns at 20-40% charge – a sign that the battery controller incorrectly determines the level of the battery.
- 🔌 Slow charging – if the smartphone charges longer than 3 hours from the original RAM.
If you find a battery bloating, immediately turn off your smartphone and do not use it until you have replaced the battery.
To check for bloating, place the Mi 9 SE on a flat surface and slightly press the back cover around the edges. If the smartphone is "playing" or there is a void under the lid, the battery is swollen.
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If the battery is swelling, you can't discharge it or push it back down, which is a temporary solution that will only make the problem worse, and the only way out is to replace it at the service center.
6 How to extend the life of the Xiaomi Mi 9 SE battery
Even if the battery is still in good condition, follow these tips to delay replacement as much as possible:
- 🔌 Avoid full discharge – charge your smartphone at 10-20% and disconnect from the network at 80-90%.
- 🌡️ Don’t overheat your smartphone – don’t leave it in the sun or near heat sources.
- ⚡ Use the original RAM – cheap charging can damage the power controller.
- 🔄 Turn off unnecessary background processes – check Settings → Battery → Battery utilization.
- 📵 Do not keep your smartphone on charge all night – after 100%, recharging continues, which accelerates wear and tear.
We also recommend turning off fast charging if you are in a hurry. Go to Settings → Battery and Performance → Fast Charging and deactivate the option. This will reduce the battery load.
If you rarely use a smartphone, store it with a charge of 40-60% in a cool place (15-25 ° C. Full charge or discharge during long-term storage is detrimental to lithium-ion batteries.